I always mount shock sensors right to the ignition wirring harness going up the steering column, and the brain as high up as possible when doing cutomers cars. When I did the alarm install on my s10, I actually put the relay pack for the alarm, and the 555L (passlock 2 bypass) way up in the dash.....like you have to pull the gauges out to get to it. As far as the rest of the alarm.....I have all of my modules (alarm brain, window automation brain, 451m) mounted on a sheet of abs, and its mounted in back of the glove box. Its hidden, but easy to get to when I want to add-on to my alarm. I have 2 shock sensors, one mounted under the dash on the ignition harness, the other in pass. side taillight. Also have a prox sensor located near the bcm.